POSS-crosslinked gel polymer electrolytes enabling low-temperature tolerant dye-sensitized solar cells

Abstract

Efficient operation of electrochemical energy devices below freezing point poses a significant challenge for enhancing their environment adaptability. This issue is particularly critical for quasi-solid-state devices those utilize gel polymer electrolytes (GPEs), since low temperature could enhance polymer crystallization in GPEs, inducing external steric hindrance that impede ionic conductivity. Herein, we utilized polyhedral oligomeric silsesquioxanes (POSS) as the eight-armed cross-linking points in an in-situ photopolymerized network, thereby constructing low-temperature tolerance GPEs for dye-sensitized solar cells (DSSCs). Compared to conventional triple-armed cross-linking, POSS could increase the disorder of the polymer network and significantly lower the glass transition temperature of the GPE from -30 °C to -48.7 °C. At an ultralow working temperature of -40 °C, the POSS-linked GPEs show a high ionic diffusion coefficient of 0.71 × 10^–6 cm² s^-1 compare to that of liquid electrolyte, ensuring that the quasi-solid-state DSSCs successfully retained 36.3 % of their room-temperature efficiency. Our work proved a design method for the low-temperature tolerance GPEs, which could enable the advanced electrochemical application in harsh climates, such as sensor, energy generation, and storage devices.